CELLS & TISSUES Chapter 3 – Pgs. 59-70 Tissue – group of cells working together to perform a specific function Histology – the study of tissues Four groups of tissues: Epithelial – Table 3-6 Connective – Table 3-7 Muscle – Table 3-8 Nerve – Table 3-8

Epithelial Found of the surfaces as covering (skin) or on inner surfaces as lining (digestive tract); many types are capable of secretion (sweat, saliva, digestive enzymes) Epithelial cells are classified according to shape and arrangement of cells – fig. 3-7

Shape squamous – flat, scale like cuboidal – cube shaped columnar – tall and narrow

Arrangement simple – single layer of cells of the same shape stratified - many layers of cells of the same shape transitional – several layers of cells with different shapes

Simple Squamous – important in the exchange of materials or for absorption; found in capillaries, alveoli (air sacs) – Fig. 3-8

Stratified squamous epithelium – Fig. 3-9 makes up epidermis of skin where surface cells are dead (keratinized) lining of mouth, esophagus, and vagina where surface cells are alive (non-keratinized) function in protection and barrier for microorganisms

Keratinized stratified squamous epithelium

Non keratinized stratified squamous epithelium

Simple Columnar Epithelial – Fig. 3-10 Single layer of cells taller than wide linings of stomach, intestines, and respiratory tract specialized cells called goblet cells secrete mucus regular cells specialize in absorption

Simple Cuboidal (glandular epithelium) – Fig. 3-8, 3-12 single layer of cube-shaped cells function in secretory activity glands; cluster or groups of secretory cells exocrine – release secretions into ducts (ex. Salivary glands) endocrine – release secretions directly into bloodstream (ex. Thyroid gland)

Stratified Transitional Epithelium – Fig. 3-11 surface cells change shape from cuboidal to squamous found in areas exposed to stress and need to be able to stretch (ex. Urinary bladder)

Pseudostratified epithelium (ciliated) columnar cells that have cilia and look as if there are two cell layers cilia sweeps mucus trapped dust and bacteria protecting lungs lines nasal cavities, trachea, and bronchial tubes also lines fallopian tubes (oviducts) and sweeps ovum from ovary to uterus

Connective Tissue Most abundant tissue type, most varied, common to all is the presence of a matrix in addition to cells – matrix is a structural network or solution of non-living intracellular material (ex. Blood matrix is plasma, bone matrix is calcium salts)

Aereola (loose connective tissue) most widely distributed connective tissue  cells are called fibroblasts which produce protein fibers (collagen and elastin) Protein fibers and tissue fluid makeup matrix found beneath epithelial tissues and body systems that have an opening to the environment for protection against microorganisms functions as “glue” that gives form to internal organs and protection

Adipose – Fig. 3-13 cells are called adipocytes matrix consists of tissue fluid and some collagen fibers function – storage of lipids/cushion for organs

Fibrous Connective Tissue – Fig. 3-14 consists mainly of parallel collagen fibers strong but flexible makes up tendons and ligaments tendon – connects muscle to bone ligament – connects bone to bone relatively poor blood supply, slow to heal

Bone – Fig. 3-15 cells are called osteocytes matrix is made of calcium salts and collagen – strong, hard, not flexible osteocytes, matrix, and blood vessels are arranged in Haversian system functions – calcium storage, support body, protect internal organs

Cartilage – Fig. 3-16 cells called chondrocytes found on surfaces of joints to prevent friction found in ear, tip of nose, wall of trachea, and in between vertebrae function – prevent friction, absorbs shock, permits movement no capillaries, gets nourishment through diffusion from surrounding tissues

Blood – Fig. 3-17 Matrix is blood plasma plasma contains dissolved salts, nutrients, and waste products function of plasma – transportation of material around the body cells of blood red blood cells carry oxygen white blood cells destroy pathogens – principle component of the immune system platelets – prevent blood loss through clotting

Red blood cell White Blood cell Platelet

Hemopoietic Tissue found in red marrow cavities of bone, spleen, tonsils, and lymph nodes function in formation of blood cells – important in defense against disease This tissue is a complex mixture of different cell types and a rich lattice

Replacement of bone marrow fat with dark red hemopoietic tissue

Muscle – specialized for contraction, when muscles contract they shorten and bring about some type of movement

Skeletal Muscle (striated or voluntary muscle) – Fig. 3-18 cylindrical, have several nuclei/cell appear striated b/c of precise arrangement of contracting proteins in cells muscles are attached to bones and move skeleton voluntary in movement, respond to nerve stimuli from brain

Smooth Muscle (visceral or involuntary) – Fig. 3-20 long, narrow, single nuclei/cell, no striation involuntary form walls of blood vessels, and organs such as stomach and intestines help regulate diameter of blood vessels and propels food down digestive tract

Cardiac Muscle (myocardium) – Fig. 3-19 branched, interlocking muscle, faintly striated, 1 nuclei/cell form walls of chambers of the heart function – pump blood, maintain blood pressure contract by themselves and therefore maintain “one” beat nerve impulses from nervous system function to increase or decrease beat as dictated by certain situations

Nerve Tissue – Fig. 3-21 cells are called neurons, supporting cells are neuroglia function – transmit electrochemical impulses structure of neuron cell body – contains nucleus axon – carries impulses away from cell body dendrite – carries impulses toward cell body each neuron has several dendrites that branch in different direction impulses are transmitted from one neuron to another at the synaptic cleft by chemical messengers called neurotransmitters make up brain, spinal cord, and nerves function – sensation, movements, regulation of body functions, organization of information for learning and memory